1. Field
The present disclosure relates generally to noise and, in particular, to reducing noise radiated by a structure. Still more particularly, the present disclosure relates to a method and apparatus for reducing noise radiated by composite and metallic structures of a launch vehicle.
2. Background
A launch vehicle is used to carry a payload from the surface of the earth into outer space. A launch vehicle may take the form of a rocket, a space shuttle, or some other suitable vehicle that is capable of carrying the payload into outer space. The payload may be, for example, a satellite or some other object that may be carried into outer space. This object may be, for example, an electronics system, a person, or some other suitable object.
With respect to operating a launch vehicle, noise generated by the launch vehicle is a concern in carrying a payload. When the launch vehicle takes the form of a rocket, a fairing may be used to enclose and/or protect the payload. For example, a fairing protects the payload against the impact of the atmosphere and may maintain a desired environment for the payload. Once outside of the atmosphere, the fairing is jettisoned or moved to expose the payload. The payload may then be separated from the launch vehicle into an orbit.
Noise shields may be employed in fairings or payloads to reduce the noise and vibrations that the payload may be exposed to during the flight of the launch vehicle.
The noise levels generated by launch vehicles may exceed 160 decibels during a launch, such as a satellite. Currently, noise control treatments may be attached to the fairings to reduce the noise inside of the fairings where the payload is located. Currently used systems include placing sound-absorbing materials on the walls of the fairings. These sound-absorbing materials may be, for example, insulating panels or mats. Additionally, some fairings may involve multiple layers of shells in which damping materials are located between the shells of the fairing. Additionally, foam blankets also may be used within the fairing.
These types of components, however, require space and increase the weight of the launch vehicle. As a result, the size and/or weight of the payload may be reduced. Additionally, these systems also increase the cost of a launch vehicle.
Therefore, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possibly other issues.